A storage system may comprise one or more devices configured to store data. The devices may be, for example, disk drives, flash memory, phase change memory (PRAM) and/or a non-volatile memory device configured to maintain the data when power is off. As an example of a storage system, a personal computer may have a disk drive configured to store data such as applications, files and/or configuration data. In addition, a flash memory and/or PRAM may be coupled to the processor in the personal computer. Other examples of storage systems are RAID storage arrays and network based storage services, such as cloud-based storage. The data stored in a storage system may be managed by storing metadata corresponding to the data item in an index. The metadata entries may include the physical location of the corresponding data item in order to easily identify and locate the data within the file or storage systems.
Deleting data is a desired operation in storage systems for many applications. For example, in some file systems, data is deleted by marking a metadata entry in the file system index to indicate the data as deleted. To securely delete the data, the physical storage locations for the data in the drives or memory of the storage system is overwritten with a bit pattern. Otherwise, the data may be recoverable.
When overwriting the data, additional overhead is incurred for secure deletes as I/O resources on the data storage device(s) are consumed during overwrites of the data to be deleted. For slow media such a tape drives, this additional overhead can tie up an I/O device and create delays within the system. In addition, when overwriting the data, adjacent data may experience write disturbance in some media types. For example, some types of media (e.g., shingled magnetic recording drives) do not efficiently support precision overwrites where nearby data might be destroyed or destabilized. Furthermore, in some memories such as flash that specify the number of read/write cycles recommended for the lifetime of the flash, overwriting data may contribute to a reduction in lifetime for the memory.
While the technology described herein is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.